Well, for one thing, you missed the Aer Lingus carryon weight limits: "Cabin baggage must weigh less than 6 kgs/13 lbs in total carried in one bag per passenger and be small enough to fit in an overhead bin or under your seat.

The maximum dimensions for a cabin bag are 56cms x 45cms x 25cms or 22in x 18in x 10in. All cabin/carry-on bags are checked and weighed at the airport. Any bags exceeding size and/or weight will be checked-in and passengers must pay a fee of €18.00 or equivalent per bag per flight for their bags when checking-in."

Also, Aer Lingus' checked baggage allowance is 5 kg larger, but it's also 2 euros more (12 vs. 10 on Ryanair). Since you don't say when you are traveling or how much luggage you have, it's hard to compare price, but it looked pretty similar to me when I checked various combinations of dates.

per the info Nabcy posted, it looks like there is a carry-on weight restriction. 13 Pounds is not much, my day bag maybe weighs that, your typical US style carry-on probably runs closer to 30 pounds

Ah yes, I did miss that part. Although they only allow 5 more kilos, and it's 2 pounds more, it's still a better deal than Ryanair, because Ryanair charges 14 POUNDS for each additional kilo. This is really concerning me because this flight will be the day before we leave from our 3 week trip, and so we'll have all our stuff at that point. I'm going to have to do some serious planning for how we'll work this out!

Even Ryanair's checked limit of 15 kg (33 lbs) is a LOT of weight. Try test-packing your bag and weighing it to give yourself an idea of what weighs what.

15 kg = 33 lb. As someone who travels a lot, this scares me. (I'm usually the one with the bright orange tag on my luggage reading "HEAVY"!) I don't bring a suitcase to Europe anymore, I use a backpack. So I will save some weight there, but when we went last time with my backpacks, I think it weighed more than 33lb. But the more I've pondered this weight issue today, the more I realize that it will just force me to pack lighter than usual. And since I know about it ahead of time, I can definitely prepare for this. I will be packing a light coat for this trip, but will definitely wear it on the plane. This won't count towards the carry-on weight, right?

Amy, probably should not comment but 33 lbs in a backpack is not packing light. You need to reduce that by close to half.

A coat that you wear onto the plane doesn't count in your baggage allowance.

I said I'd pack "lighter than usual." I don't pack light. I'm usually the one at the check-in counter taking jeans out of my suitcase to stuff into my carry-on so I can get my suitcase under 50 lb. I will pack the very most that I can without being charged. ;-)